X-linked midline defects.

Opitz and Gilbert [Am J Med Genet 12:443-455, 1982] have postulated that the midline may be a kind of developmental field. Although developmental field defects (primary malformations) usually occur sporadically, in some instances they can be caused by a single gene mutation. We report on a family in which the occurrence of midline defects was consistent with X-linked inheritance. Anomalies present in the family include hydrocephalus, anencephaly, cleft lip, congenital heart defect, renal agenesis, and hypospadias.